Absorbent articles such as disposable diapers, incontinence pads, and catamenial napkins generally include an absorbent core for receiving and holding body exudates. The absorbent core typically includes a fibrous web, which can be a nonwoven, airlaid web of natural or synthetic fibers, or combinations thereof. A class of particulate absorbent materials known as superabsorbent polymers or absorbent gelling materials can be incorporated into the fibrous web to improve the absorption and retention characteristics of the fibrous web.
Because absorbent gelling materials are generally significantly more expensive than readily available natural or synthetic fiber materials (e.g., cellulose fibers), it is advantageous to reduce the quantity of absorbent gelling material in the core. Rather than uniformly distributing such particles throughout the entire core, it is desirable to distribute the particles in the absorbent core in a predetermined manner such that the particles are located where they will be most effective in acquiring and retaining body exudates.
While various means of forming uniformly distributed particle streams and applying them to portions of the absorbent core (such as entraining individual particles in an air stream) have been developed, these methods typically either require multiple feed mechanisms or overapplication of particles to selectively-adhesive-coated zones of the core. The use of multiple feed mechanisms multiplies the capital cost required to produce such absorbent cores, while the overapplication of particles to selective adhesive zones increases material waste and accompanying material costs.
Accordingly, it would be desirable to provide an improved method and apparatus for making absorbent structures having discrete bands or regions of absorbent particulate gelling materials separated by substantially particle-free zones which minimizes the equipment required.
It would also be desirable to provide an improved method and apparatus for making absorbent structures having discrete bands or regions of absorbent particulate gelling materials which reduces the amount of loose absorbent gelling material particles generated by the manufacturing process and provides reduced material waste.